A longitudinal study of the language development of children of adolescent mothers followed 20 adolescent and 20 older mothers from their children's birth through three years of age. This report is based on data collected from a subsample of 20 mothers. Mother-child interactions in feeding, teaching, and play at eight months and two years were videotaped and transcribed, and the children's utterances were coded for grammatical complexity, discourse variables, and pragmatic variables. The results indicate significant differences between adolescent and older mothers, especially at eight months. At that stage, older mothers were more responsive to their infants and more likely to impute intentionality to their infants' noncommunicative behaviors, an activity linked to rate of acquisition. While the adolescent mothers appeared to enjoy interacting with their infants as evidenced by a high percentage of initiations and equal simultaneous interaction, they reacted to their children more concretely, rarely reading anything into their actions or verbalizations. Parallel trends were found at two years. There did not appear to be any significant difference in the children's general linguistic abilities at two years, but there were differences in standardized test scores at eight months, two years, and three years. (MSE)